French jets in fresh air strikes on IS

French warplanes have carried out fresh raids overnight against the Islamic State stronghold of Raqa in northern Syria, destroying a command centre and a training facility, the defence ministry says.

"For the second time in 24 hours the French military conducted an air raid against Daesh in Raqa in Syria," it said in a statement on Tuesday, using another name for the jihadist group.

President Francois Hollande has vowed to hit back at IS "without mercy" after Friday's attacks in Paris, the bloodiest on its territory.

Ten Rafale and Mirage 2000 fighters carried out the raid at 0030 GMT (1130 AEDT), dropping 16 bombs, the defence ministry said.

"Both targets were hit and destroyed simultaneously," it said.

"Conducted in co-ordination with US forces, the raid was aimed at sites identified during reconnaissance missions previously carried out by France."

France has carried out air raids against IS in Syria since September but stepped up its raids after Friday's attacks, with 10 warplanes dropping 20 bombs on jihadist targets in Raqa on Sunday.

The US and France have also decided to increase their exchange of intelligence on potential targets.

France is set to further intensify its operations against the jihadists in Syria through the information acquired and upcoming deployment of the aircraft carrier Charles de Gaulle, which will triple its capacity to strike.